Fire dampers



Dec. 1, 1970 F. w. PANTLAND 3,543,439

' FIRE DAMPERS Filed Oct. 7, 1968 s Sheets-Sheet 1 Dec. 1, 1970 F. w. PANTLAND 3,543,439

mm; mmrmns Filed Oct. 7, 1968 G Sheets-SW7 vv Z H mm 6 Sheets-Sheet 3 F. W. PANTLAND FIRE DAMPERS Filed Oct. 7, 1968 FIRE DAMPERS 6 Sheets-Sheet 4.

Filed on. 7, 1968 Dec. 1, 1970 F. w. PANTLAND FIRE DAMPERS 6 Sheets-Sheet 5 Filed Oct. 7, 1968 Dec. 1, 1970 w, PANTLAND 3,543,439

- FIRE DAMPERS Filed Oct. '7, 1968 6 Sheets-Sheet 6 United States Patent 3,543,439 FIRE DAMPERS Frederick William Pautland, 120 Marsden Road, West Ryde, New South Wales, Australia Filed Oct. 7, 1968, Ser. No. 765,324 Int. Cl. E05f /20 US. Cl. 49-7 16 Claims ABSTRACT OF THE DISCLOSURE Dampers in air-conditioning or other ducts are held open by a thermo-responsive device which operates to close the damper under the influence of an elevated temperature. When the damper closes, its blades overlap the surrounding frame, thereby eliminating the peripheral space normally left between the blades and that frame. This prevents jamming of the blades and also provides a complete peripheral seal. The blade bearings are protected against grit or corrosion by being immersed in wax which normally holds them rigid but which melts under elevated temperatures and permits the necessary movement for closure of the blades.

This invention relates to improvements in fire dampers and in particular, but not exclusively, to fire dampers for insertion in ventilating or air-conditioning ducts and similar passages where, in the event of fire, hot air, fumes, smoke or flames could be passed from one portion of a building to another.

In some countries it is already a legal requirement that fire dampers should be provided in air-conditioning or ventilating ducts in buildings, particularly multi-storey buildings. In most other countries, it is becoming the common practice to install such dampers when a new building is in course of erection, and it is believed that such a practice will soon be legally enforced in almost every country.

Fire dampers for the above purpose may be installed either in the individual outlets of air conditioning or ventilating ducts into rooms or corridors, and so on, or may be disposed in a horizontal section of a main duct between different floors. Such dampers essentially consist of one or more horizontally pivoted damper blades similar to louvres which are normally held in an open, substantially horizontal position by thermo-responsive means which, when subjected to heat above a predetermined temperature, release the damper blade or blades which are so biased as to fall into a vertical plane to close the duct. The thermo-responsive means may be a thermostaticallyoperated trigger mechanism or a fusible link made from a metal, such as a lead/tin/bismuth alloy, which will melt when subjected to a predetermined temperature. Alternatively, the link may be one of the thermoplastic resins such as, for instance, P.V.C., polypropylene or nylon.

The damper blades are preferably so arranged that when open, their planes lie horizontally and parallel with the air flow, and so that when closed, any onrush of fumes or expanding gases tends to increase their closing and sealing action. The blades may be either disc shaped or rectangular, depending upon the cross-section of the duct, a clearance gap needs to be left between each vertical edge of the blades (when closed) and the adjacent surface of each mullion. Such a clearance, although essential to ensure correct functioning of such a blade, also reduces the efficiency of the damper by leaving a passage for fumes and heat between the end of each blade and its associated mullion and it has thus previously only been possible to ensure the correct operation of such a fire damper by reducing its etficiency.

Similarly, with disc-like dampers in ducts of circular cross-section, a peripheral space has had to be left around the disc-shaped blade for a similar reason.

The object of the present invention is to provide a fire damper in which the above disadvantages are eliminated.

Where, in the present specification, terms of orientation such as vertical or horizontal are used, these refer to the aspect of the integers when mounted in a frame in a horizontal portion of a duct, except that in the case of rectangular ducts the side edges of the damper blades lying adjacent the vertical mullions of the frame are referred to as the vertical edges whether the blades are in their open or their closed position.

According to the invention, there is provided a fire damper for inclusion in a portion of an air duct, said fire damper including an open frame secured to the inner surface of said duct transversely thereof and having pivotally mounted therein one or more damper blades, said frame including at least one flange extending transversely inwardly of said duct and a web extending parallel with the Wall of said duct, the, or each, said blade being pivoted at opposite ends in, and extending across, said duct, said blade or blades being normally biassed to lie in a vertical plane and being of such length that when in said vertical plane they overlap said flange or flanges, and thermoresponsive means for retaining said blade or blades in a horizontal plane and for allowing it or them to move into a vertical plane under the influence of a predetermined elevated temperature applied to said thermoresponsive means.

A better understanding of the invention may be obtained from the following description of exemplary forms thereof, it being appreciated, however, that the forms described are exemplary only and that the full scope of the invention is not intended to be limited by any specific terms necessarily used for the purpose of this description.

Furthermore, it is to be understood that the invention is not limited to a fire damper having any specific number of blades, so that although in one form the following description is given to fire dampers having four blades, this number is given in an exemplary manner and is not intended to imply any precise limitation.

In the accompanying drawings:

FIG. 1 is an isometric view of a fire damper according to one form of the invention and having a single tier of blades, which are shown in their open position,

FIG. 2 is a section on the line 2--2 of FIG. 1, but showing the blades in closed position and the fusible link broken,

FIG. 3 is a detail of the hinges of FIGS. 1 and 2,

FIG. 4 is a section on the line 4-4 of FIG. 3,

FIG. 5 is a section of portions of two adjoining blades in their closed position,

FIG. 6 is a vertical section of one form of fusible link,

FIG. 7 is a section on the line 77 of FIG. 2 showing the sealing of the vanes,

FIG. 8 is a section similar to FIG. 2, but showing twin tiers of vanes in their open position,

FIG. 9 is a detail of a trunnion connection for the damper blades,

FIG. is a part section on the line 1010 of FIG. 9,

FIG. 11 is a view similar to FIG. 1 of a further form of the invention,

FIG. 12 is a section, similar to FIG. 2, of the embodiment of FIG. 11 and taken on the line 12-12 of that figure, and

FIG. 13 is a view similar to FIG. 12 but showing the blade in open position.

Referring now to FIGS. 1 to 10 of the drawings, and assuming that the damper is to be used in a ventilating duct (and it can equally well be used in an air-conditioning duct, or, in fact, any duct used for the passage of a gaseous fluid) it includes a rectangular surrounding frame 10 consisting of two horizontally spaced mullions 12 and two vertically spaced transoms 14, or a transom 14 and a sill 14a.

The mullions 12 (or jambs) each includes a rectangular sectioned vertical channel 16, the outer surfaces of the web 18 of each of which face each other across the space intervening between the opposite mullions 12. The side flanges 20, 22 of the channel of each mullion 12 are planar in form and at its free edge each channel flange 20, 22 is turned outwards away from the channel normally to the flange so that each out-turned portion 24, 26 lies parallel with the web 18.

In the web 18 of each channel towards the flange 20 (i.e., eccentrically of the web) may be located an aperture 28 for a bearing member 30 for that end of each blade 32. This aperture 28 may be formed in an annular plate 34 secured to the said outer surface of the web 18, the periphery of the aperture 28 in the plate 34 being dished towards the inside of the frame as at 36 to cooperate with a dimple 38 formed in the web 18 so that its concavity faces towards the plate 34, with the dished portion 36 of which it co-operates to form a spherical socket 40 in which is located a bearing member for the blade pivot 44.

The bearing member has a part spherical head 42 for snug location within the socket 40 and has a hollow cylindrical spigot 46 extending slightly outwardly of the aperture 28 in the annular plate 34 into the central space of the frame 1.

The bearing members are vertically spaced down the channel webs 18 in such a manner that when the blades 32 pivot downwards into their vertical closed position the upper horizontal edge of the top damper blade 32a will lie closely against the adjacent surface of the upper transom as at 48 in FIG. 2, the lower horizontal edge of the lower blade 32b will rest closely against the adjacent surface of the lower transom 14 as at 50 in FIG. 2 and the intervening blades 32 will overlap each other as at 52 in FIG. 5. If desired, a strip 54 may be secured at each end to the web 18 of each channel and to the inside surfaces of the upper and lower transoms 14 so that no free space exists between the upper and lower blades 32a and 32b and the transoms 14 when the blades 32 are vertical as in FIG. 2. The strip 54 may as shown in FIG. 2, be the vertical web or limb of an angle-sectioned member, the other leg or limb of which is secured to the lower tarnsom 14.

The blades 32 are rectangular strips of metal having an overall length such that they will pass freely between the opposite turned back portions 24, 26 of the channel flanges 2i) and will rest against and overlap the outer surface of corresponding flanges 20 of the opposed channels 16. Due to this overlap, a good seal can be obtained between the blades 32 and the flanges 20 while still leaving ample clearance for lengthwise heat expansion of the blades 32 without jamming.

Although substantially planar in general form, the blades 32 are arranged to interengage when closed and for this purpose, each is formed with a longitudinal reentrant V-shaped fold 56 parallel with and adjacent its upper edge and a similar V-shaped fold 58 at its lower edge (see FIG. 5), the apices of the folds projecting to- 4 wards that side of the blade 32 which lies uppermost when the blades are in their open position and being so spaced on the blades that when the blades 32 are in their vertical close-d position the V-shaped fold 56 near the upper edge of a lower blade 32 rests within the V-shaped fold 58 on the lower edge of the next upper blade 32.

To pivot the blades 32 in their respective hollow spigots 46, a bracket 60 (FIGS. 2, 3 and 4) is secured adjacent each end of each blade 32 and includes a pivot pin 62 which engages within the respective spigot 46 with freedom for movement in each axial direction to allow for lengthwise expansion or contraction of the blade 32 without jamming or dislodgment.

Alternatively, the bearing members 30 may be formed in the brackets 60 (described hereunder) and the pivot pins 62 be secured in the webs 18.

The upper corner of each blade 32 at each end has a rectangular cut-out portion 33 (FIG. 1) so that these corners of the blades 32 do not jam against the channnel flange 20 and prevent the blades from assuming an open horizontal position.

Due to the ball and socket mounting of the bearing members in the mullions or in the brackets 60 (FIG. 4), any distortion in the blades 32 is compensated for by the bearing members.

The pivot brackets 60 are mounted on the blades 32 on the reverse surface from the projections caused by the folds 56, 58. Centrally of the length of each blade 32 and adjacent the lower edge of each is secured a trunnion bracket 63 in which is pivoted a control arm 64 which extends past the lower edge of each blade. Each control arm 64 is secured in spaced relation to a vertical control rod 66, which is associated a thermo-responsive device 68, which, when subjected to an elevated temperature, will release the blades so that they pivot downwards under their own weight, to closed position, Although this thermoresponsive device 68 may be a high temperature thermostat for actuating a simple latching means, it preferably consists, as shown particularly in FIG. 6, of a bracket or arm 70 secured towards the upper end of the control rod 66 (see also FIG. 2) and having its free end connected to a portion 72 of the duct thereabove by an intervening fusible link 68, which may be based upon one of the known fusible metal alloys such ar lead/tin/bismuth or may be one of the known thermoplastics such as nylon, P.V.C. or polypropylene.

As shown by way of example, only, in FIG. 6, such a link 68 may consist of a metal cup 74 secured, with its open end upwards, to the arm 70 and a pin 76 located at the lower end of a connecting wire, rod or metal strap 78 secured to the duct portion 72. With the pin 76 in position in the cup 74, and the blades 32 in the open position the cup 74 is filled with a lead/tin/bismuth alloy 75, preferably having a melting point of the order of F. As will be appreciated, this particular construction is not essential so long as the two portions connected by the fusible material will freely separate at the desired temperature. It will be obvious also, that the fusible link will not normally be fabricated in situ, but will be prefabricated and be connected between the arm 70 and member 78 when required for installation.

The fusible link 68 is located on the side of the duct from which air normally flows, i.e., on the upstream side.

One of the commonest causes of malfunction in previous fire dampers has been due to rust, grit or a build-up of verdigris over a period of years in and-around the bearings, causing the assemblies to become inoperative when the need arose.

In order to avoid this difficulty in the present invention, when the ball and socket bearing assembly (FIG. 4) has been assembled, the whole assembly is dipped in beeswax 80, which is allowed to harden before the blade pivots 62 are inserted in the hollow spigot 46. This effectively seals formation of verdigris and against the penetration of moisture. When, however, the damper is subjected to extreme heat, even after years of non-use, the beeswax 80 melts and frees the pivots 62 and also, in its molten state, acts as a lubricant therefor.

The hollow spigot 46 is made of sintered bronze and its closeness of fit in its socket 40 is such that even if the spigot 46 melts under extreme heat, that end of the blade 32 will drop by only about thus allowing a positive closure still to be maintained.

The upper portion of each blade 32 above the upper V- section fold is offset from the plane of the lower portion by the thickness of the metal of the blade, thus allowing a face-to-face contact between the overlapping portions of adjacent blades.

Suitable means 82 are provided near the lower edge of the lower blade and on the lower transom 14a automatically to lock the blades in their closed positions.

Although the above description refers only to a singletier damper arrangement, FIG. 8 shows a twin-tier arrangement which provides an even greater damping effect than the previously described single tier assembly.

As shown in FIG. 8 two tiers of blades 32, as shown in FIGS. 1 and 2, are arranged in reversed parallel spaced relation, the tier on the right of FIG. 8 being located on the upstream side of the normal air flow in the duct.

Although a twin-tier installation may be readily effected merely by taking two single-tier assemblies as shown in FIGS. 1 and 2, reversing one of these about its vertical center line and making the adjustment of the fusible link arrangement as described hereunder, it may be found more convenient to combine the two tiers in a single frame 10.

For this purpose, the frame 10 is made of a greater dimension longitudinally of the duct, this dimension being approximately twice that of the FIG. 1 embodiment. The

web 18 of the channel is similarly twice as wide as that of the single-tier assembly.

Blades 32, which are identical with those of the single tier form, are pivoted in reversed aspect on pivot pins 62 and are located in the hollow spigots 46 as shown in FIG. 4, the sockets 40 being located in two horizontally separated vertical rows, one row adjacent the flange 20 of each channel 16 and one row adjacent the flange 22 of the channel.

Other than this, and the fusible link connection described hereunder, the arrangement and structure of all integers is as described hereabove in connection with FIGS. 1 to 7.

The fusible link 68 is located on the upstream side of the damper, and its lower, or cup portion 74 is connected to the arm 70 on that side of the damper.

Instead of the strap, rod or wire 78 being connected to the duct at 72 (FIG. 2) a flexible member 78a, preferably a flexible steel wire rope, is taken from the pin 76 and is passed upwards above the upper blade 32a of each row and then downwards, where it is connected to the arm 70a in such manner that it is under a slight tension when the blades 32 are in their open position. When the fusible link 68 melts and releases the pin 76., the blades 32 of both rows fall to their closed positions.

As will be obvious, the fusible link 68 can be dispensed with and substituted by a plastic or other insert having a melting point of the order of 160 F. or the flexible wire rope 78a may itself be dispensed with and substituted by a plastic cord having a similar melting point.

The member 78a may be passed through a tub 90 secured beneath or above the transom 14. If secured below it, the upper edge of the upper blades 32a will be suit ably recessed so that the tube does not interfere with their complete closure.

In both embodiments of the invention, the control arms 64 are rigidly secured to the control rod or rods 66 as the blades 32 pivot from a horizontal to a vertical position when closing, means, as shown in FIG. 9, being provided to permit the arms 64 to pivot in the trunnion brackets 63.

For this purpose, the trunnion brackets 63 are made in two mirror image halves 84, (see FIGS. 9 and 10). Each half is provided with half of a hemispherical socket 86 in which is located a substantially spherical head 88 formed on the end of the control arm 64 remote from the associated control rod 66.

With the blades 32 open, the control arms 64 lie in the broken line position of FIG. 9 relative to the blades 32 (see also FIGS. 1 and 8) while in the closed position of the blades, the arms 64 lie in the full line position of FIG. 9 relative to the blades (see also FIG. 2). As in the case of the bearing assembly of FIG. 4, the spherical heads 88 may have beeswax 80 applied before being mounted in the trunnion brackets 63.

As will be obvious from a comparison between FIGS. 1 or 8 and FIG. 2, when the fusible link 68 releases, the control rod or rods 66 move downwards and inwardly of the frame 10 as the blades 32 move to their closed positions.

Although referred to herein as a fire damper, the invention is equally applicable for damping the flow of hot air, fumes, smoke or flames and is not intended to be limited to any specific purpose within that range.

Where the invention is to be usable for preventing the flow of fumes or smoke not accompanied by excessive heat, the thermo-responsive means may be provided with additional means so that fusing heat may be applied thereto from an external source.

Such means (not shown) may consist of an electrical resistance element wound around a portion of the plastic or other insert or wound around the cup 74 or embedded in the alloy 75 and connected to an electric circuit through a suitable switch. In the event of a flow of smoke or fumes having insuflicient inherent heat to release the thermoresponsive device, it could then be released by applying an electric current to the heating element.

Also, as it is often necessary to enable fire prevention or other authorities to test the operation of the dampers without interfering with the thermo-responsive devices, the straps 78, instead of being secured to the ducts as at 72 may be secured to means operated by an electric motor or other device whereby, upon operation of the motor, the blades will be allowed to fall to their vertical position and then be raised back to their horizontal position. Electric contacts operated by the blades in each position may be used to indicate these positions by tell-tale lights on a common control panel.

Such modifications will be obvious to those skilled in the art and require no further description.

Referring now to FIGS. 11 to 13, the damper 102 here shown is for use in a cylindrical duct 104 and is in the form of a disc which is pivoted in a bearing bracket assembly 106, as shown and described in relation to FIGS. 3 and 4, on pivot pins 108. The pivots 108 may be secured through the wall of the duct 104 or may be located in a separate cylindrical sleeve 110 inserted between two sections of the duct 104.

Within the duct 104 or the sleeve 110 is inserted an angle-sectioned annular frame 112, the web 114 of which lies parallel and secured to the inside surface of the duct 104 or sleeve 110 and the flange 116 of which lies normal to said surface and extends inwardly of the duct. The flange 116 has a gap 118 on the line of the pivot pins 108 to permit the disc 120 to move from the FIG. 11 and 13 position to the FIG. 12 position while still peripherally overlapping the flange 116.

The damper 102 is normally held in its open position, as in FIGS. 11 and 13, by a fusible link 68 such as that shown in FIG. 6 or by any other suitable thermo-responsive means as previously described, and the damper 102 is provided with a counterweight 122 which, when the thermo-responsive means such as the link 68 are subjected to heat above a predetermined temperature and release the disc 120, biasses the damper to its closed position as in FIG. 12.

As the disc 120 pivots to the closed position its lower edge passes over a leaf spring 124 which rises behind the closed disc and holds it firmly against the flange 116.

The disc 120 is offset along the centre line of the pivots 108, as at 126 so that when in its closed position the upper half of the disc will rest snugly against one side of the flange 116 and the lower half will rest snugly against the other side of the flange 116.

Other than as explained hereabove, the embodiment of FIGS. 11 to 13 is constructed and operates precisely as the embodiment of FIGS. 1 to 10.

What I claim is:

1. A fire damper for inclusion in a portion of an air duct, said fire damper comprising an open frame adapted for being secured to the inner surface of the duct transversely thereof, blade means mounted in said frame, flange means extending perimetrally along said frame and transversely and inwardly thereinto, a web extending from said flange longitudinally in said frame, means pivotably connecting said blade means to said web for pivotal movement about an axis offset from said blade means, and thermo-responsive means engaging said blade means to hold the same normally horizontally and to release the same to a vertical position under the influence of gravity when the temperature reaches a predetermined level, said blade means comprising a plurality of blades each having a width to overlap and interengage one another at their upper and lower edges when vertical, said blades having a length to overlap said flange means and hence form a solid barrier when the blades are vertical, whereby to close in entirety the opening in said frame.

2. A fire damper according to claim 1, wherein said frame includes sides arranged in rectangular outline and said flange means comprises a flange extending along each side of said frame.

3. A fire damper according to claim 2 wherein each blade includes a bearing bracket secured to the underside of said blade, said bearing bracket including a pivot pin pivotally engaged in a bearing in said web.

4. A fire damper according to claim 2 wherein each said blade has two parallel V-section folds formed therein to form parallel grooves in the surface thereof which is lowermost when said blades lie horizontal one said fold lying adjacent and parallel to a pivoted edge of said blade and the other lying at the lower edge of said blade, said folds being so disposed that the projection caused by the fold near the pivoted edge of a lower blade will lie within the depression caused by the fold at the lower edge of the next upper plate when said blades move into the said vertical plane.

5. A fire damper according to claim 2 wherein each said blade has a control arm extending normally from the edge thereof remote from the pivot axis, said control arm having a free end operatively associated with said thermoresponsive means.

6. A fire damper according to claim 3 wherein each said bearing comprises a hemispherical dimple expressed outwardly in said web and a plate secured to said web inwardly of said dimple and having an annular outwardly-directed part-spherical recess formed therein, a hollow cylindrical spigot having a substantially spherical head located in the recess formed by co-operation of said dimple with said annular recess, said spigot projecting from said annular recess and having said pivot pin located therein.

7. A fire damper according to claim 6, wherein said spigot and bearing are immersed in beeswax prior to insertion of said pivot pin in said hollow spigot.

8. A fire damper according to claim 7, wherein said hollow spigot is fabricated from sintered bronze.

9. A fire damper according to claim 1, including two horizontally spaced vertical tiers of said blades, the blades in one said tier, when in said horizontal plane, being directed away from the blades in the other said tier.

10. A fire damper according to claim 1 wherein said thermo-responsive means is a fusible link having sepa- V rable portions normally connected together by material capable of melting or fusion at a predetermined elevated temperature;

11. A fire damper according to claim 10, wherein said material is a lead/tin/bismuth alloy.

12. A fire damper according to claim 10, wherein said material is a thermoplastic material.

13. A fire damper according to claim 10, wherein said predetermined temperature is of the order of F.

14. A fire damper according to claim 5 wherein each blade has a control arm attached thereto, the free ends of said control arms being each secured in spaced relation to a vertical control rod and said control rod having an arm secured to and extending normally therefrom, the free end of the latter said arm being secured to said thermo-responsive means.

15. A fire damper according to claim 14 wherein each said control arm is attached to a respective blade through a trunnion bracket permitting vertical angular movement of said control arm relative to said blade upon pivotal movement thereof.

16. A fire damper accorling to claim 1, wherein said means pivotably connecting said blade means to said web comprises a bearing bracket secured to said blades on the undersides thereof, and pin and bearing means be tween said bracket and web, said pin and bearing means comprising a part spherical recess with a spigot rotatably mounted therein, and a pin in said spigot.

References Cited 1 UNITED STATES PATENTS 1,077,847 11/1913 McLane 49--7 X 1,196,051 8/1916 Watson 497 1,618,551 2/1927 Perry et a1 497 2,267,140 12/ 1941 Schottenberg 4992 X 2,270,073 l/ 1942 Merry 497 X 2,314,003 3/1943 Mader 4992 X 2,863,374 12/1958 Hinden 4992 3,254,451 6/1966 Wills et al. 4992 X 3,260,018 7/1966 Schuh 497 2,287,262 6/ 1942 Merry. 3,123,098 3/1964 Bishop 98-110 X 3,154,332 10/1964 Scheublein et al 287-87 3,283,691 11/1966 Reiter 98-86 X DENNIS L. TAYLOR, Primary Examiner US. Cl. X.R. 98-121 

